This invention relates to an improved measuring apparatus which includes magnetoresistance elements arranged opposite to a scale, such as a magnetic type rotary scale or a linear scale, and is adapted to measure a relative amount of movement between the scale and the magnetoresistance element array through the utilization of a variation in the resistive value of the magnetoresistance elements due to the effect of a magnetic pattern on the magnetic scale.
A measuring apparatus is known which measures the amount of rotation, movement, etc., of an object. This type of measuring apparatus has been utilized in various fields thanks to its high accuracy and, recently, it has been applied to the field of automatic control. The apparatus includes a magnetic pattern of a given pitch type and a sensor arranged opposite to the magnetic scale. With either the magnetic scale or sensor fixed, and the other connected to a moving object the measuring apparatus can measure the amount of movement of the object by electrically processing a signal which is obtained from the sensor when the object is moved.
In this case, magnetoresistance element sections include magnetoresistance elements arranged at a pitch corresponding to the pitch of the magnetic pattern on the magnetic scale. The measuring apparatus generates an electric signal corresponding to the amount of movement through the utilization of a variation in the resistive value of the magnetoresistance element due to the effect of the magnetic pattern on the magnetic scale.
In the above-mentioned measuring apparatus, the pitch of the magnetic pattern on the magnetic scale is determined in accordance with a resolution on measurement. The magnetoresistance elements of the sensor are arranged to have a pitch corresponding to the pitch of the magnetic pattern. That is, the pitch of the magnetic pattern must have a mutually corresponding relation to the pitch of the magnetoresistance elements.
For this reason, when a plurality of kinds of magnetic scales of different resolutions are to be used, it is necessary to prepare a plurality of kinds of sensors having magnetoresistance elements arranged at a pitch corresponding to the pitch of the magnetic pattern on the respective scale. This often results in a complex measuring operation.